Meta-stable sites in amorphous carbon lattice generated by rapid quenching of liquid diamond

Abstract

Formation of amorphous structure of carbon by rapid quenching of the liquid phase was investigated by molecular dynamic (MD) simulation using Tersoff's empirical potential. Physical properties of crystalline diamond, such as lattice parameter, surface energy and elastic constants were well described by the present calculations. The amorphous structure was generated by rapid quenching the melted diamond lattice from 10,000K at various cooling rate from 1.25×1015K/s to 6.25×1015K/s. In the amorphous carbon lattice, only first and second nearest order were observed at 1.52 and 2.52 ？, respectively. However, when the cooling rate was larger than 6×1015K/s, it was observed that significant number of atoms exist at a meta-stable site at about 2.2 ？. This site was commonly observed regardless to the preparation method. Relaxation behavior was investigated by annealing of the quenched sample at elevated temperatures. It was observed that the relaxation was governed by Arrhenius type reaction with the activation barrier of 4.8×10-14 erg/atom.